Since humans began weather modification in the 1940s, warm cloud catalysts have always been a worldwide problem that is difficult to crack.
In the theoretical research on warm cloud precipitation mechanisms, the theory of collision, coalescence and breaking has been explicitly proposed. However, in the research on warm cloud catalysts, the idea that has been used for a long time is that hygroscopic substances can absorb moisture to grow at a pressure lower than the saturation vapor pressure, as for the hydrophilicity of the cloud condensation nuclei, there is no distinction, which hides the cognition to the wetting nuclei, no detailed research on surface tension difference is made with regard to the phenomena of large cloud droplets coalescing with small cloud droplets, and little is known about the source regions and features of the atmospheric aerosol particles capable of forming large water droplet-started collision mechanism.
In the related art, hygroscopic substances such as sodium chloride, calcium chloride, urea or ammonium nitrate, etc. are generally used as warm cloud catalysts; and these common hygroscopic substances all have certain corrosivity (which will corrode spraying devices), and are easy to agglomerate, and when such type of hygroscopic substances are used as warm cloud catalysts, since the falling speed of the catalyst particles is too fast, and the factor of surface tension of the aqueous solution thereof is not taken into account, the effect of artificial precipitation is extremely unsatisfactory, and at present, there is no repeatable successful case. Thus, it is difficult to practically use such kind of warm cloud catalysts in production and life.
Therefore, it is a technical problem to be solved urgently by people to provide a warm cloud catalyst which directly uses the theory of collision, coalescence and breaking as the guidance, is non-corrosive, is not easy to agglomerate, can continuously grow cloud droplets into raindrops and can be practically used.